1. Field of the Invention
The present invention relates to methods for building masonry structures such as brick and block walls, which are usually assembled by skilled masons by applying mortar to the top and side surfaces of the bricks or blocks and stacking them in a stable configuration, and to apparatus for applying the mortar by extruding it onto a surface at a selected rate.
2. Discussion of the Prior Art
Construction with traditional bricks or blocks is expensive, not only because materials are costly commodities, but because the labor required to build masonry structures is also costly. Therefore, the time taken by the building process is of unrelenting concern to property owners, developers and contractors, with the result that no mason can work quickly enough to satisfy everybody. The manual application of mortar in the correct amounts and locations on the top and side surfaces of the bricks or blocks and stacking them in a stable configuration and properly aligned takes time, and rushing a skilled mason may adversely impact the quality of the mason's work.
There have been attempts to find a way of automating some of the operations performed by the mason, and such efforts to partially automate the procedure of applying mortar to the top surfaces of a wall of bricks or blocks are described in several patents, such as U.S. Pat. No. 2,341,691 to Ciceske, U.S. Pat. No. 2,591,377 to Sadler, U.S. Pat. No. 3,545,159 to Brewer, U.S. Pat. No. 3,826,410 to Meyer, U.S. Pat. No. 4,135,651 to Hession et al., and U.S. Pat. No. 4,352,445 to Cusumano et al. These references show mortar applying devices that are pushed or pulled across the top surface of a wall. In addition, U.S. Pat. No. 2,683,981 to Richey, U.S. Pat. No. 3,791,559 to Foye, and U.S. Pat. No. 3,887,114 to Villanovich show wheeled mortar applying devices that are propelled across the top of a wall under construction by an operator turning a hand crank that drives the wheels. Most of these patents show the automated deposition of two beads of mortar along the top outer edges of blocks in a wall.
Many mortar applying devices use internal elements which contact the mortar while it is being deposited. For example, U.S. Pat. No. 3,162,886 to Wise discloses a mortar applying device which includes an auger for driving the mortar toward exit ports, U.S. Pat. No. 2,683,981 to Richey discloses the use of impellers to stir the mortar, U.S. Pat. No. 3,791,559 shows the use of mortar working blades, and U.S. Pat. No. 4,352,445 to Cusumano et al. shows the use of paddles to even out the mortar in the beads which have been laid.
On the other hand, U.S. Pat. No. 4,135,651 to Hession et al. and U.S. Pat. No. 3,545,159 to Brewer show the use of gravitational forces in dispensing the mortar on the blocks in a wall, and U.S. Pat. No. 3,826,410 to Meyer and U.S. Pat. No. 4,043,487 to Price show the use of gravitational forces assisted by vibration.
In the cases where gravity is used as the mortar feed mechanism, care must be taken to assure that the mortar is dispensed at approximately the same rate irrespective of the amount of mortar present in the feed mechanism hopper. Some prior mortar applying devices which use gravity suffer from the fact that mortar will be dispensed faster at the beginning of a run, when the hopper is full and a greater downward force is exerted by the weight of the mortar in the hopper, than at the end of the run when the hopper is nearly empty and a lesser downward force is exerted by the remaining mortar in the hopper. Such a situation leads to an uneven thickness of mortar in the wall, and this is unacceptable for proper construction.
Another problem arises when mortar is pumped to a tool for applying or dispensing, and then flow is stopped; for such stoppage can cause the mortar to start to cure in the tool, causing anything which contacts the stagnant mortar to become jammed, occluded, smeared or plugged, and this presents serious clean up problems for the user. If mortar is allowed to harden on the moving element, as would happen if the mortar applying device was not thoroughly washed at the end of a day, the mason is forced to chisel the element free of dried or curing mortar before the device can be used again.
There is a need, therefore, for an efficient, cost-effective and easy-to-use system and method for selectively extruding and applying a layer of mortar upon a selected surface which is to receive a masonry structure such as a course of bricks or blocks. Such a surface may be a concrete slab such as a patio, a pad or other surface, or may be an existing course of blocks or bricks.